A combined cytologic and biochemical analysis of the relationship between RNA and hemoglobin synthesis in RBC differentiation is planned. These studies will be performed on an experimentally-induced erythroid system in the European newt, Triturus cristatus. By means of radioautographic and biochemical methods, the various types of RNA synthesized and accumulated in specific erythroid stages will be examined and related to the onset of hemoglobin synthesis. Emphasis will be placed on ribosomal and hemoglobin messenger RNA. In addition, correlated electron microscopic and biochemical studies of nuclear RNA particles in different erythroid cells will be undertaken. The objectives of the proposal are: (1) a descriptive analysis of biochemical events in RBC differentiation, and (2) to determine the extent to which the process of RBC differentiation is governed by transcriptional and translational control mechanisms.